Recurrent Selection as a Basis for the Widespread Dissemination and Cultivation of Onions: Examples From Northeastern Brazil

Goal: This study aimed to review phenotypic recurrent selection (PRS) in the onion development for northeastern Brazil. Theoretical Framework: Domesticated in the Central Asia (35°N and 50°N), onion is one of the main vegetable species widely cultivated around the globe. PRS methods are efficient for genetic gains (GG), maintaining variability in the population. Method: Cultivars of two onion-breeding programs for the Brazil Northeast region were analyzed to evaluate the PRS efficiency. Results and discussion: 1. PRS resulted in the development of cultivars Valeouro Ipa 11 and Franciscana IPA 10, at Belém do São Francisco (08°45'S, 38°57'W), replacing 70% of imported cultivars. 2. PRS for resistance to Thrips tabaci (09°09’S, 40°22’W), a pest of global importance, in the 'BRS Alfa São Francisco' resulted in GG of 6%/cycle, with a bulb yield of 32.1 ton.ha-1, contrasting with 15.9 and 14.0 ton.ha-1 of 'Alfa Tropical' and 'IPA 10', respectively (p<0.01). In direct planting and high population density, BRS Alfa São Francisco produced 60 ton.ha-1 in the second semester. 3. The PRS for external brownish or purplish cataphylls and greater thickness (09°09’S, 40°22’W), in the CNPH 6400, resulted in GG/cycle of 6.83% and 11.54% in the brownish population and 7.84% and 10.92% in the purplish population, evaluated in two locations. Research implications: These examples emphasize the efficiency of PRS for accumulating favorable alleles, allowing the recommendation of onion cultivars in areas different from the domestication region. Originality/Value: The adopted approach have distinguished the massal selection from recurrent selection.